In industry, there are a large number of plants which emit noise and for reasons of protection of the environment are therefore the subject of noise attenuation measures. One such measure is to cover the plant in question on all sides by a noise attenuation hood in order to correspondingly reduce noise emissions. It is self-evident that for cost reasons such a noise attenuation hood in terms of size must be dimensioned as far as possible so that it encloses the plant in question in a manner which is as space saving as possible. On the other hand, for maintenance operations and/or repair work it may be necessary to work on the plant which is enclosed by the noise attenuation hood. For this, it is frequently necessary to erect a platform on which work can be carried out on the plant with the hood open.
Special conditions prevail in this case in power plants. The power plant operator plans downtimes for its power plants each year in order to reliably maintain the power plants and also to achieve high availability and remaining running time of the power plant.
In order to minimize the costly downtime as much as possible, a detailed planning of the maintenance operations is necessary. The success of such planning is determined especially by the effectiveness of the tools used and infrastructure during the downtime. As a result of highly specialized tools and a corresponding infrastructure, the labor expenditure can be reduced, the downtime and the costs associated therewith can be reduced and safety during the downtime can be increased. The working space which is made available for the maintenance is frequently a problem which results in delays and even accidents.
In combined cycle power plants, the turbomachines (gas turbines, steam turbines) are provided with the noise attenuation hoods which are mentioned above (see U.S. Pat. No. 6,477,843 B2, for example, which is incorporated by reference) in order to limit the noise to an acceptable and legally prescribed level. For maintenance times and downtimes, parts of the noise attenuation hood must be removed in order to improve access to the plants. This requires expenditure of labor and time and employs crane systems which at the same time are urgently required elsewhere.
In order to improve the situation, a (free-standing) working platform is sometimes erected on the plant, as is schematically shown in FIG. 1. FIG. 1 shows in section a noise-emitting industrial plant (turbine plant) 30 with a noise attenuation hood 26 which encloses a turbine 11, the machine axis of which is perpendicular to the plane of the drawing and which is indicated by a circle. Details of the turbine 11, such as the support structure or the fresh air intake and exhaust gas duct, are not shown for the sake of simplicity. Inside the noise attenuation hood 26, level with the turbine 11, provision can be made for an internal walkway 13 which leads along the machine in the axial direction. For working on the turbine 11, a separate working platform 27 is now erected outside the noise attenuation hood 26 and is supported on the ground 31 by supports 28 and made safe by means of a guard rail 29. By means of corresponding openings (not shown in FIG. 1) in the noise attenuation hood 26, the working personnel can carry out the necessary work on the turbine 11 from the working platform 27.
The working platform 27 is designed so that it can support the tools, pieces of equipment, work benches, office equipment and also instruments and individual components—up to a weight of 25 kg, for example—which are necessary for the work during the disassembly and assembly processes. To this end, a carrying capacity of the working platform 27 of 500 kg/m2, for example, is necessary. The removal of insulating covers, fuel lances, burners, devices and heavy bolts can thus be carried out via the working platform and not via steps which would bring along a high risk of injury. However, such working platforms are frequently not available and cannot be replaced by a construction with a scaffold either.
The described prior art therefore has the following disadvantages:                The removal of parts of the noise attenuation hood requires considerable expenditure of labor and time        Valuable cranage time is employed for the removal        Erection of a separate working platform is costly        A working platform is frequently not available        The construction of a working platform involves additional risks of injury        The final assembly of the noise attenuation hood is again costly in labor and time        The parts which accumulate during scheduled maintenance operations inside the noise attenuation hood are removed via an internal working platform, which necessitates considerable expenditure of labor and time and in many cases also entails valuable cranage work, and also involves risks of injury.        